Volume 20, Issue 1 , Pages 9-16, January 2009
Clinical Predictors of Transient Ischemic Attack, Stroke, or Death within 30 Days of Carotid Artery Stent Placement with Distal Balloon Protection
Article Outline
Purpose
Carotid artery stent placement has been accepted as an effective alternative to carotid endarterectomy (CEA), especially in patients at high risk in the setting of CEA. The purpose of this study was to determine potential clinical risk factors for the development of postprocedural neurologic deficits after carotid artery stent placement.
Materials and Methods
The clinical characteristics of 58 patients (49 men, nine women; 41 at high risk with CEA, 17 at low risk; median age, 70 years) who underwent carotid artery stent placement with distal balloon protection for 65 hemispheres/arteries (31 asymptomatic lesions and 34 symptomatic lesions) and the combined 30-day complication rates (transient ischemic attack [TIA], minor stroke, major stroke, or death) were analyzed.
Results
Six patients (9.0%) experienced a TIA and one patient (1.5%) had a major stroke (1.5%) within 30 days of the procedure. There were no deaths, so the overall 30-day combined stroke and death rate was 1.5%. The χ2 test revealed that advanced age (>75 years) was a significant clinical predictor of 30-day combined neurologic complications and major adverse effects (P < .01). In addition, a symptomatic lesion was marginally associated with the 30-day incidence of neurologic ischemia on the ipsilateral side (P = .049).
Conclusions
Our data suggest that carotid artery stent placement with distal balloon protection can be performed with similar periprocedural complication rates as CEA. CEA should be the first-line treatment in the management of patients older than 75 years of age.
Abbreviations: CEA, carotid endarterectomy, EPD, embolic protection device, NASCET, North American Symptomatic Carotid Endarterectomy Trial, TIA, transient ischemic attack
ALTHOUGH carotid endarterectomy (CEA) has been the gold standard treatment for carotid artery stenosis (1, 2, 3, 4), carotid artery stent placement with or without embolic protection devices (EPDs) has been investigated as an endovascular alternative to CEA for the treatment of obstructive atherosclerotic carotid artery disease (5, 6, 7, 8, 9, 10, 11). The Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy trial (12) showed that protected carotid artery stent placement is not inferior to CEA in patients at high risk. However, the Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis trial (7), which compared carotid artery stent placement versus CEA in patients with symptomatic carotid stenosis of more than 60%, recently reported higher rates of stroke or death in the carotid artery stent placement group. In addition, the Carotid Revascularization Endarterectomy versus Stenting Trial (5, 6), a prospective multicenter randomized study comparing patients with symptomatic and asymptomatic severe stenosis, is under way.
There are currently three types of EPDs on the market, namely distal occlusion balloons, distal filter devices, and proximal occlusion balloons (13, 14). Although these devices work very differently from one another (15), they are all designed to capture and remove debris during angioplasty and stent placement procedures, thereby providing protection against distal embolization and preventing intraprocedural complications. The present study involved a retrospective review of periprocedural results (≤30 days) based on prospectively collected data on the use of distal occlusion balloons, which were the most commonly used EPDs in Japan until the Angioguard XP device (Cordis, Miami Lakes, Florida) became available in 2008.
Materials and Methods
Patient Population
Patients presenting with stenosis of at least 70% of the internal carotid artery were offered a choice between surgical and endovascular treatment. Surgical or endovascular treatment was also indicated in patients with at least 50% carotid stenosis if they had recurrent stroke. Asymptomatic patients with at least 60% carotid stenosis were also treated if they had bilateral carotid lesions or multiple-vessel disease, even though the current literature worldwide states that asymptomatic patients are treated only when the stenosis is 70% or more. The degree of carotid stenosis was at least 90% in 26 of 65 lesions (40%), 70%–89% in 32 lesions (49%), and 50%–69% in seven lesions (11%). Carotid artery stent placement was mainly indicated in patients at high risk (including those who were ineligible for the North American Symptomatic Carotid Endarterectomy Trial [NASCET] [1], those older than 75 years of age, and those with concomitant coronary artery disease), patients with echogenic plaque, and patients who expressed a preference for the procedure. Considering the higher surgical risk, recurrent stenosis after CEA was a definite indication for carotid artery stent placement in this study. Between May 1999 and July 2008, carotid artery stent placement with distal balloon occlusion devices was performed in 58 patients for 65 hemispheres/arteries at two institutions, the National Cardiovascular Center and Hamamatsu Rosai Hospital. Among seven patients with bilateral severe carotid stenosis, bilateral lesions were treated on the same day in two. Advanced age was defined as age greater than 75 years. The degree of carotid artery stenosis was measured by digital subtraction angiography according to the method used in the NASCET (1).
Neurologic Complications and Major Adverse Events
The clinical characteristics and combined 30-day complication rates (ie, transient ischemic attack [TIA], minor stroke, major stroke, or death) were analyzed. Neurologic deficits other than TIA were classified as minor stroke (ie, a new neurologic deficit persisting for >24 hours with a modified Rankin score of <3 at 30 days after treatment) or major stroke (modified Rankin score of ≥3 at 30 days after treatment). Major adverse events were defined as any stroke, myocardial infarction, or death within 30 days of carotid artery stent placement.
Imaging Studies
Preoperative echography was performed routinely at the National Cardiovascular Center to evaluate the plaque morphology. Preoperative computed tomographic angiography was performed routinely at Hamamatsu Rosai Hospital except in patients with chronic renal failure. Preoperative digital subtraction angiography was performed routinely but not exclusively. The incidence of new periprocedural ischemic events was determined by examining preoperative images with diffusion-weighted magnetic resonance (MR) images obtained 2–5 days postoperatively. Any new hyperintense lesion on diffusion-weighted MR imaging was interpreted as a posttreatment ischemic lesion.
Premedication
One or two antiplatelet drugs were administered for at least 3 days before the procedure. Although 100 mg aspirin was administered as a premedication in the early protocol, two antiplatelet drugs and a statin were routinely administered before the procedure in the present protocol. Two antiplatelet drugs were administered in the last 38 cases, and a statin was administered in 27 cases. The antiplatelet regimen currently used included aspirin 81–100 mg plus clopidogrel 75 mg, ticlopidine 100–200 mg, or cilostazol 100–200 mg. In the present protocol, two antiplatelet agents were given for at least 3 months after the procedure and at least one antiplatelet agent was given throughout the follow-up period.
Therapeutic Procedure
With the exception of one procedure performed via the transcervical approach with a 6-F guiding catheter, all percutaneous procedures were performed via the right common femoral artery with an 8-F or a 9-F guide catheter delivered into the common carotid artery and placed proximal to the stenotic lesion. Unfractionated heparin (5,000 U) was routinely administered intravenously just after the introducer sheath placement to increase the activated clotting time to 2–2.5 times the baseline level. A temporary transvenous pacemaker was prophylactically used in 40 procedures (62%), usually in patients with concomitant coronary artery disease or heavily calcified lesions. In patients without a temporary pacemaker, atropine was routinely administered just before predilation.
The vessel was predilated with a percutaneous transluminal angioplasty balloon catheter placed across the stenosis. Typically, monorail-type balloons such as the Amiia balloon (Cordis) were used in the predilation. The balloons used were 3.5–4.5 mm in caliber and 20–30 mm in length in most cases, but varied according to the lesions. A self-expandable stent was then placed across the dilated segment over the guide wire with use of a stent delivery system. EasyWall (Boston Scientific, Osaka, Japan), Smart (Cordis), and Precise (Cordis) stents were used in four, 30, and 31 cases, respectively. Since Precise stents became available in Japan, they have been used exclusively. Before January 2003, the cerebrum was protected from distal embolism with use of Tranvas protective balloons (Kaneka Medix, Kanagawa, Japan; Fig 1). After predilation at the minimum pressure and subsequent stent deployment, postdilation was performed with cerebral protection with a Tranvas balloon, combined with 0.035-inch guide wire–compatible peripheral angioplasty. In the 40 cases treated since February 2003, all predilation, stent deployment, and postdilation procedures were performed under cerebral protection with a GuardWire (Medtronic, Minneapolis, Minnesota), intermittently in some cases (Figure 2, Figure 3, Figure 4, Figure 5). In two cases, proximal endovascular blockage of blood flow was also performed during predilation, as described previously (16). Postdilation was performed after stent placement in 45 cases (69%) in which residual stenosis was more than approximately 30% after stent deployment. The balloons used in the postdilation were 4.5–5.5 mm in caliber and 20 mm in length in most cases.
Figure 1.
The Tranvas device is 2.7 F in diameter and consists of a percutaneous transluminal angioplasty balloon on the proximal side (arrow) and a silicone protective balloon on the distal side (arrowhead).
Figure 2.
Severe right internal carotid artery stenosis above the bifurcation. Selective digital subtraction angiography was performed after the guiding catheter was placed in the common carotid artery.
Figure 3.
The GuardWire has been placed across the lesion and the protection balloon (arrowhead) inflated.
Figure 4.
Inflation of the angioplasty balloon (Amiia; 5 mm × 40 mm) under cerebral protection.
Figure 5.
Final result after balloon angioplasty and placement of a 10-mm × 40-mm stent in the right internal carotid artery.
Statistical Analysis
The associations between potential clinical risk factors and postprocedural complication rates within 30 days after carotid artery stent placement were assessed by univariate analysis. The χ2 test was used for comparison of discrete variables, and P values less than .05 were considered to indicate significance.
Results
The total study population consisted of 58 patients who underwent carotid artery stent placement in 65 lesions (49 men, nine women; 41 at high risk with CEA, 17 at low risk; median age, 70 years; age range, 50–83 y). There were 31 asymptomatic lesions (48%) and 34 symptomatic lesions (52%). In the group of symptomatic patients, five (15%) presented with amaurosis fugax and the remaining 29 (85%) presented with a hemispherical TIA or minor stroke. There were 59 atherosclerotic lesions (91%), four restenoses after previous CEA, and two stenoses after radiation treatment. The procedures were performed at the National Cardiovascular Center (n = 22) and Hamamatsu Rosai Hospital (n = 36).
Table 1 summarizes the demographic and clinical characteristics of the patients. All lesions received stents, and technical success was achieved in 64 of 65 lesions (98.5%). The residual stenosis was less than 30% in all patients except one who had severe hypotension during the procedure and in whom postdilation was withdrawn. Prophylactic occlusion during balloon inflation and stent placement was well tolerated in 60 procedures (92%), and use of the distal occlusion balloon did not produce any vasospasm in our series. One patient with 70% stenosis of the contralateral internal carotid artery became completely intolerant to protection balloon inflation. He lost consciousness and developed seizures during the postdilation procedure. He developed hemiparesis and aphasia soon after deflation of the occlusion balloon, despite evacuation of 40 mL floating debris.
Table 1. Summary of Patient Characteristics
| Clinical Situation | Incidence |
|---|---|
| Hypertension | 44 (76) |
| Diabetes mellitus | 30(52) |
| Hyperlipidemia | 29(50) |
| Smoking | 19(33) |
| Congestive heart failure | 6(10) |
| Coronary artery disease | 20(34) |
| Planned CABG creation | 6(10) |
| Chronic renal failure | 8(14) |
| Arteriosclerosis obliterans | 5(8.6) |
| Malignancy | 3(5.1) |
| Previous neck radiation | 1(1.7) |
| Advanced age (>75 y) | 13(22) |
| Contralateral lesion | |
| Occlusion | 3(5.1) |
| Severe stenosis | 14(24) |
Table 2 shows the postprocedural complication rates within 30 days. For the entire study population, the 30-day TIA rate was 9.0%, the stroke rate was 1.5%, and the death rate was zero. Neither symptomatic hyperperfusion nor hemorrhagic stroke was observed in this series. All TIAs and all but one stroke were ischemic on the ipsilateral side. A stroke occurred just after deflation of the protective balloon. Five of six TIAs were observed during the procedure, three of which occurred before cerebral protection, such as in passing a guide wire through the stenotic lesion. One patient with bilateral severe carotid artery stenosis had a TIA resulting from hemodynamic change on the contralateral side more than 24 hours after the procedure. This patient was awaiting three-vessel coronary artery bypass graft surgery, and had a myocardial infarction 6 days after carotid artery stent placement. Therefore, the overall rate of perioperative stroke/myocardial infarction/death was 3.1%. Postoperative MR imaging, including diffusion-weighted imaging, was performed after all carotid artery stent placement procedures except in one patient who had a major stroke. Silent cerebral ischemia detected by diffusion-weighted MR imaging was present after 13 carotid artery stent placement procedures (20%). Transiently, bradycardia was observed in 17 procedures (27%), hypotension was observed in 23 lesions (37%), and bradycardia with hypotension was observed in seven procedures (11%). However, sustained bradycardia and sustained hypotension were observed in only one procedure each (1.5%).
Table 2. Summary of Perioperative Complications
| Complication | Incidence |
|---|---|
| Neurologic ischemic complication | |
| Major stroke | 1(1.5) |
| Transient ischemic attack | 6(9.0) |
| Myocardial infarction | 1(1.5) |
| Silent cerebral ischemia detected by diffusion-weighted MR imaging | 13(20) |
| Hemodynamic instability | |
| Hypotension | 23(37) |
| Bradycardia | 17(27) |
| Others | |
| Anemia | 5(7.7) |
| Pneumonia | 1(1.5) |
| GI bleeding | 1(1.5) |
| Inguinal hematoma | 2(3.1) |
| Mortality | 0 |
| 30-day stroke/death rate (%) | 1.5 |
| 30-day stroke/MI/death rate (%) | 3.1 |
The associations between potential clinical risk factors and neurologic complication rates within 30 days after carotid artery stent placement are summarized in Table 3. The most significant predictor of 30-day postprocedural neurologic ischemia was advanced age (>75 years). Elderly patients had higher complication rates than younger patients (38.5% vs 3.8% for the combined outcome measure of TIA, stroke, or death; P = .001; odds ratio, 15.6). Advanced age was also a significant predictor of stroke, myocardial infarction, or death at 30 days (P = .004). Although a symptomatic lesion did not significantly affect the occurrence of TIA or stroke within 30 days after the procedure, symptomatic patients had marginally significantly higher neurologic complication rates on the ipsilateral side than asymptomatic patients (17.6% vs 0%; P = .049). Although only one of 49 patients (2.0%) at high risk with CEA had a major stroke, CEA risk did not significantly affect the complication rates, as mentioned earlier. The overall 30-day complication rates in the groups at high and low risk with CEA were 8.2% and 6.3%, respectively (P = .75).
Table 3. Associations between Potential Clinical Risk Factors and Neurologic Complication Rates within 30 Days after Carotid Artery Stent Placement
| Risk Factor | Stroke | TIA | None | P Value |
|---|---|---|---|---|
| Hypertension | .75 | |||
| Yes | 1 | 5 | 43 | |
| No | 0 | 1 | 15 | |
| Diabetes mellitus | .077 | |||
| Yes | 0 | 1 | 35 | |
| No | 1 | 5 | 23 | |
| Hyperlipidemia | .63 | |||
| Yes | 0 | 3 | 28 | |
| No | 1 | 3 | 30 | |
| Smoking | .20 | |||
| Yes | 1 | 3 | 17 | |
| No | 0 | 3 | 41 | |
| Age (y) | .0011 | |||
| >75 | 1 | 4 | 8 | |
| ≤75 | 0 | 2 | 50 | |
| Sex | .49 | |||
| Male | 1 | 6 | 49 | |
| Female | 0 | 0 | 9 | |
| Stenosis | .17 | |||
| ≥90% | 1 | 4 | 22 | |
| <90% | 0 | 2 | 36 | |
| Contralateral lesion | .28 | |||
| Severe stenosis or occlusion | 1 | 2 | 16 | |
| Less severe or no stenosis | 0 | 4 | 42 | |
| Symptoms | .16 | |||
| Symptomatic | 1 | 5 | 28 | |
| Asymptomatic | 0 | 1 | 30 | |
| Ulcer formation | .090 | |||
| Yes | 1 | 2 | 10 | |
| No | 0 | 4 | 47 | |
| CEA risk | .75 | |||
| High risk | 1 | 5 | 43 | |
| Low risk | 0 | 1 | 15 | |
| Intraoperative hypotension | .087 | |||
| Yes | 1 | 4 | 18 | |
| No | 0 | 2 | 40 | |
| Hospital | .40 | |||
| NCVC | 0 | 1 | 23 | |
| HRH | 1 | 5 | 35 | |
| Emboli protection device | .25 | |||
| Tranvas | 0 | 1 | 24 | |
| GuardWire | 1 | 5 | 34 |
Discussion
Protected carotid artery stent placement has been accepted as an effective alternative to CEA, and is currently under investigation. Three types of EPDs are currently available, namely distal occlusion balloons (17, 18, 19, 20), distal filter devices (21, 22, 23, 24, 25), and proximal occlusion balloons (26, 27, 28). Many kinds of EPDs have been developed and described. However, because all EPDs have theoretical advantages and limitations, the ideal device has not yet been determined. The Achilles heel of distal occlusion devices is transient occlusion of blood flow. However, they are easy to use and relatively safe for crossing stenotic lesions, even in tortuous vessels. In the present series, one patient with severe stenosis of the contralateral internal carotid artery became completely intolerant to protection balloon inflation. He lost consciousness and developed seizures during the postdilation procedure. He had a major stroke after deflation of the occlusion balloon, possibly because of incomplete evacuation of floating debris after stent placement. Thus, a filter-type protection device should be the first choice in cases of intolerance, allowing constant cerebral perfusion during carotid artery stent placement. However, filter devices seem unable to prevent microemboli (<100 μm), and are associated with risks of filter clogging, vasospasm, and filter entrapment in the stent (13, 21, 22, 23). Proximal occlusion balloons seem to be the most reliable because they avoid embolization during initial passage of the guide wire and throughout the procedure (27), but they are more cumbersome to use. They are exclusively used in our practice for carotid lesions in which a floating thrombus is apparent and for nearly occluded lesions in which even passing a guide wire poses a risk of distal embolism. In two cases with nearly occluded lesions, a reversal of flow was obtained by inflating balloons in the external and common carotid arteries during predilation. After the stent was above the stenosis, the reverse flow was discontinued and the procedure was undertaken under cerebral protection with a GuardWire (Medtronic) as described in the “Seat Belt and Air Bag” technique (16). In our series, the perioperative complication rates were relatively low for carotid artery stent placement with use of distal balloon protection devices compared with other reports of protected carotid artery stent placement with use of various protection devices.
Predilation was performed in all patients in this series. In our opinion, balloon-type and filter-type EPDs work quite differently from each other. When using the GuardWire system, predilation is more important, and postdilation can be omitted when complete or near-complete dilation is achieved after stent deployment. Conversely, when we use filter-type EPDs, postdilation is more important, and predilation should be minimized or primary stent implantation should be performed if feasible to minimize the duration of filter deployment. The interval between balloon angioplasty and removal of the filter should be minimized because floating debris after angioplasty or stent placement can potentially cause filter fogging and, eventually, perioperative stroke (29).
Advanced age was the most significant predictor of neurologic ischemia and major adverse events within 30 days of carotid artery stent placement in our series. Although advanced age was not proven to be a risk factor in carotid artery stent placement in some series (30, 31), most authors agree that advanced age should be a significant predictor of postoperative complications of carotid artery stent placement (32, 33, 34). Although the 38.5% risk of TIA or stroke in elderly patients seems extremely high, an 8.3% risk of stroke is compatible with that reported in the Carotid Revascularization Endarterectomy versus Stenting Trial lead-in phase (33). Unfavorable arterial anatomic characteristics such as aortic arch elongation, arch calcification, and arch vessel origin stenosis have been proposed as causes (32). However, previous reports, including subanalyses of the NASCET and the European Carotid Surgery Trial, did not find advanced age to be a risk factor for CEA (35, 36). In the Stent-Protected Angioplasty versus Carotid Endarterectomy trial (37), a recently published prospective randomized study, the perioperative risk in elderly patients (age >75 years) was higher in the carotid artery stent placement group than in the CEA group, whereas the perioperative complications were equivalent in the two groups for younger patients (age ≤75 years). Therefore, the current evidence suggests that older patients should preferentially undergo CEA when they have another risk factor with CEA. We must also keep in mind that medical therapy alone is reasonable for elderly patients with a life expectancy of less than 5 years.
In our series, symptomatic plaque was marginally associated with ipsilateral neurologic ischemia, in accordance with previous reports (30, 34). Both the Stent-Protected Angioplasty versus Carotid Endarterectomy trial (37) and the Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis trial (12) failed to show noninferiority of carotid artery stent placement in patients with symptomatic carotid artery stenosis. However, the 30-day incidences of any stroke or death in the carotid artery stent placement groups in these trials were higher than previously reported. One of the possible explanations is that the target lesions were limited to symptomatic carotid artery stenosis. “Vulnerable” plaques are atherosclerotic plaques that have a high likelihood of causing thrombotic complications, such as lesions with a large lipid-necrotic core, a thin fibrous cap, macrophage-dense inflammation, or intraplaque hemorrhage (38, 39). Given that symptomatic carotid disease resulting from the generation of thromboemboli has been associated with plaque instability and intraplaque hemorrhage (40, 41, 42), it is reasonable that symptomatic lesions are likely to cause neurologic ischemia as a result of the carotid artery stent placement procedure, which involves crushing atherosclerotic plaque material against the vessel wall with a high-pressure balloon. In our series, stents with an open-cell design were used in 61 of 65 procedures (94%). Stents of a closed-cell design might be better for the treatment of symptomatic or vulnerable plaques, as suggested by Hart et al (43). In our current protocol, a statin is routinely administered irrespective of the low-density lipoprotein level before and after carotid artery stent placement because the marked low-density lipoprotein reduction induced by statin use has been reported to cause atherosclerosis regression and plaque stability (44, 45). Preoperative statin treatment has also been reported to reduce the incidence of stroke, myocardial infarction, and death from CEA (46) and carotid artery stent placement (47). The role of statin administration during carotid interventions should be elucidated more thoroughly in future prospective trials.
The overall 1.5% risk of stroke or death in our series and the 2.9% risk of stroke or death in symptomatic patients are equal to or better than the risks in the CEA groups in the Asymptomatic Carotid Atherosclerosis Study (3) and NASCET (1). The 4.1% risk of stroke, myocardial infarction, or death in the group at high risk with CEA is more favorable than that reported in the stent arm of the Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy trial (33), and lower than the 7.6%–8.5% risk in the trial of Halliday et al (5) and the 8.5% risk in the SECURITY trial (6). However, the reported postoperative risk for CEA seems to be improving (48, 49). This is possibly explained by carotid artery stent placement being selected in patients at high risk in the CEA setting with severe carotid artery stenosis, as well as recent progress in medical treatment, anesthesiology, and surgical techniques. Further evidence can be acquired through ongoing trials such as the Carotid Revascularization Endarterectomy versus Stenting Trial (5, 6). Significant technologic progress will also certainly be made in the field of cardiovascular implantable devices. The common goal of vascular and intravascular surgeons for improving operative risks is ongoing.
Carotid artery stent placement with distal balloon protection has been demonstrated to be feasible and safe, even in patients at high risk, with a periprocedural complication rate equal to or better than those for CEA in the Asymptomatic Carotid Atherosclerosis Study (3) and NASCET (1). Advanced age was the most significant predictor of neurologic complications. Symptomatic plaque was also significantly associated with ipsilateral neurologic complications. CEA should be the first-line treatment in the management of patients older than 75 years, in whom medication alone is less effective.
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PII: S1051-0443(08)00902-0
doi:10.1016/j.jvir.2008.10.008
© 2009 SIR. Published by Elsevier Inc. All rights reserved.
Volume 20, Issue 1 , Pages 9-16, January 2009
